U.S. patent application number 16/962358 was filed with the patent office on 2020-11-05 for method and system for providing flight guidance for an aircraft.
The applicant listed for this patent is C SERIES AIRCRAFT MANAGING GP INC.. Invention is credited to Silviu CEPARU, James P. DWYER, Nadiya NAN.
Application Number | 20200348694 16/962358 |
Document ID | / |
Family ID | 1000004987712 |
Filed Date | 2020-11-05 |
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United States Patent
Application |
20200348694 |
Kind Code |
A1 |
CEPARU; Silviu ; et
al. |
November 5, 2020 |
METHOD AND SYSTEM FOR PROVIDING FLIGHT GUIDANCE FOR AN AIRCRAFT
Abstract
Methods and systems for providing vertical flight guidance for
an aircraft. Vertical flight guidance for the aircraft is provided
by an aircraft computer in an altitude capture mode for commanding
the aircraft to capture a target altitude. At least one engine
inoperative condition is detected by the computer, while in the
altitude capture mode. In response to detecting the at least one
engine inoperative condition, the computer causes an automatic
transition (e.g., no pilot action on a flight level change (FLC)
pushbutton on a flight control panel) of the vertical flight
guidance for the aircraft from the altitude capture mode to an
already existing mode that is flight level change with modified
control parameters and provides vertical flight guidance in the
flight level change mode for commanding the aircraft to capture the
target altitude while maintaining airspeed of the aircraft
substantially at a target airspeed.
Inventors: |
CEPARU; Silviu; (Quebec,
CA) ; DWYER; James P.; (Wichita, KS) ; NAN;
Nadiya; (Quebec, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
C SERIES AIRCRAFT MANAGING GP INC. |
Quebec |
|
CA |
|
|
Family ID: |
1000004987712 |
Appl. No.: |
16/962358 |
Filed: |
January 16, 2019 |
PCT Filed: |
January 16, 2019 |
PCT NO: |
PCT/CA2019/050059 |
371 Date: |
July 15, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62618186 |
Jan 17, 2018 |
|
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G05D 1/042 20130101;
B64F 5/60 20170101 |
International
Class: |
G05D 1/04 20060101
G05D001/04; B64F 5/60 20060101 B64F005/60 |
Claims
1. A computer-implemented method for providing vertical flight
guidance for an aircraft, the method comprising: providing, by a
computer, vertical flight guidance for the aircraft in an altitude
capture mode for commanding the aircraft to capture a target
altitude; detecting, by the computer, at least one engine
inoperative condition while in the altitude capture mode; in
response to detecting the at least one engine inoperative
condition, the computer transitioning the vertical flight guidance
for the aircraft from the altitude capture mode to a flight level
change mode and providing vertical flight guidance in the flight
level change mode for commanding the aircraft to capture the target
altitude while maintaining airspeed of the aircraft substantially
at a target airspeed.
2. The method of claim 1, wherein detecting the at least one engine
inoperative condition comprises detecting the at least one engine
inoperative condition at takeoff.
3. The method of claim 1, wherein the target airspeed is a takeoff
safety speed of the aircraft.
4. The method of claim 1, wherein the target airspeed is a takeoff
safety speed of the aircraft plus a predetermined value.
5. The method of claim 1, wherein detecting the at least one engine
inoperative condition comprises detecting the at least one engine
inoperative condition at a time of a go-around maneuver.
6. (canceled)
7. The method of claim 1, wherein detecting the at least one engine
inoperative condition comprises detecting the at least one engine
inoperative condition when airspeed of the aircraft is below an
airspeed threshold.
8. The method of claim 7, wherein the flight level change mode is a
second flight level change mode having a higher vertical
acceleration limit than a vertical acceleration limit of a first
flight level change mode and a lower minimum vertical speed level
than a minimum vertical speed level of the first flight level
change mode; and wherein the method further comprises
transitioning, by the computer, the second flight level change mode
to the first flight level change mode when airspeed is above the
airspeed threshold.
9. The method of claim 7, wherein the airspeed threshold is a
takeoff safety speed of the aircraft.
10. (canceled)
11. (canceled)
12. (canceled)
13. (canceled)
14. The method of claim 8, further comprising transitioning, by the
computer, the first flight level change mode to the second flight
level change mode when complementary filtered airspeed of the
aircraft is below a takeoff safety speed minus 3 knots, aircraft
altitude is below a reference altitude by a set altitude amount,
and aircraft altitude is below the target altitude.
15. The method of claim 8, further comprising transitioning, by the
computer, the first flight level change mode to the second flight
level change mode when complementary filtered airspeed of the
aircraft is below a missed approach climb speed minus 3 knots,
aircraft altitude is below a reference altitude by a set altitude
amount, and aircraft altitude is below the target altitude.
16. (canceled)
17. (canceled)
18. (canceled)
19. A system for providing vertical flight guidance for an
aircraft, the system comprising: a processing unit; and a
non-transitory computer-readable memory having stored thereon
program instructions executable by the processing unit for:
providing vertical flight guidance for the aircraft in an altitude
capture mode for commanding the aircraft to capture a target
altitude; detecting at least one engine inoperative condition while
in the altitude capture mode; in response to detecting the at least
one engine inoperative condition, transitioning the vertical flight
guidance for the aircraft from the altitude capture mode to a
flight level change mode and providing vertical flight guidance in
the flight level change mode for commanding the aircraft to capture
the target altitude while maintaining airspeed of the aircraft
substantially at a target airspeed.
20. The system of claim 19, wherein detecting the at least one
engine inoperative condition comprises detecting the at least one
engine inoperative condition at takeoff.
21. The system of claim 19, wherein the target airspeed is a
takeoff safety speed of the aircraft.
22. The system of claim 19, wherein the target airspeed is a
takeoff safety speed of the aircraft plus a predetermined
value.
23. The system of claim 19, wherein detecting the at least one
engine inoperative condition comprises detecting the at least one
engine inoperative condition at a time of a go-around maneuver.
24. (canceled)
25. (canceled)
26. The system of claim 19, wherein detecting the at least one
engine inoperative condition comprises detecting the at least one
engine inoperative condition when airspeed of the aircraft is below
an airspeed threshold, and wherein the flight level change mode is
a second flight level change mode having a higher vertical
acceleration limit than a vertical acceleration limit of a first
flight level change mode and a lower minimum vertical speed level
than a minimum vertical speed level of the first flight level
change mode; and wherein the program instructions are further
executable by the processing unit for transitioning the second
flight level change mode to the first flight level change mode when
airspeed is above the airspeed threshold.
27. The system of claim 19, wherein detecting the at least one
engine inoperative condition comprises detecting the at least one
engine inoperative condition when airspeed of the aircraft is below
an airspeed threshold, and wherein the airspeed threshold is a
takeoff safety speed of the aircraft.
28. (canceled)
29. (canceled)
30. The system of claim 19, wherein detecting the at least one
engine inoperative condition comprises detecting the at least one
engine inoperative condition when complemented deceleration of the
aircraft drops below a deceleration threshold, wherein the flight
level change mode is a second flight level change mode having a
higher vertical acceleration limit than a vertical acceleration
limit of a first flight level change mode and a lower minimum
vertical speed level than a minimum vertical speed level of the
first flight level change mode; and wherein the program
instructions are further executable by the processing unit for
transitioning the second flight level change mode to the first
flight level change mode when complemented deceleration is above
the deceleration threshold.
31. (canceled)
32. The system of claim 26, wherein the program instructions are
further executable by the processing unit for transitioning the
first flight level change mode to the second flight level change
mode when complementary filtered airspeed of the aircraft is below
a takeoff safety speed minus 3 knots, aircraft altitude is below a
reference altitude by a set altitude amount, and aircraft altitude
is below the target altitude.
33. The system of claim 26, wherein the program instructions are
further executable by the processing unit for transitioning the
first flight level change mode to the second flight level change
mode when complementary filtered airspeed of the aircraft is below
a missed approach climb speed minus 3 knots, aircraft altitude is
below a reference altitude by a set altitude amount, and aircraft
altitude is below the target altitude.
34. (canceled)
35. (canceled)
36. (canceled)
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of the International
Application No. PCT/CA2019/050059, filed on Jan. 16, 2019, and of
U.S. provisional Application Ser. No. 62/618,186, filed on Jan. 17,
2018, the entire disclosures of which are incorporated herein by
way of reference.
FIELD OF THE INVENTION
[0002] The present disclosure relates generally to aircraft
guidance, and more specifically to providing vertical flight
guidance for an aircraft to achieve airspeed protection.
BACKGROUND OF THE INVENTION
[0003] After liftoff of an aircraft with high rate of climb (RoC)
and low setting of the preselected altitude, a flight guidance
system switches early (i.e., far from the target altitude) from a
takeoff mode to an altitude capture (ALT CAP) mode to achieve a
target altitude. In the altitude capture mode, airspeed of the
aircraft is controlled by thrust command provided by an automatic
throttle or a manual throttle. If a single engine failure (OEI)
occurs in the altitude capture mode, the airspeed of the aircraft
can no longer be controlled on thrust (i.e., automatically or
manually) because thrust is saturated at a maximum when the single
engine failure occurs. If the OEI occurs right after the ALT CAP
mode became active compounded with the aircraft being far from the
target altitude (e.g., early ALT CAP activation due to high rate of
climb) without pilot intervention to change the aircraft pitch
attitude (i.e. pitch down), the airspeed decays below safe
operating values (e.g., V2 in takeoff). A similar scenario may
occur while preforming go-around maneuvers.
[0004] However, pilot intervention is not an acceptable solution at
least on platforms with a high level of integration of the
Automatic Flight Control System (AFCS). The low altitude capture
with OEI is a critical phase of flight (i.e., takeoff or go-around)
and is a high crew workload/stress operational scenario. Moreover,
on integrated AFCS (e.g., as the case of C Series and Global 7000
aircraft), manual intervention would require the crew to ignore the
flight director (FD) vertical guidance (i.e. referenced to target
altitude). Such situation has been deemed unacceptable by the
authorities (e.g., Transport Canada Civil Aviation (TCCA), European
Aviation Safety Agency (EASA) and Federal Aviation Administration
(FAA)). The FD lateral and vertical guidance may be integrated
(e.g., by a single FD cue), thus the FD guidance cannot be
deselected (e.g., FD OFF) because the crew needs the FD lateral
guidance while they need to ignore the vertical guidance.
[0005] Thus, there is a need to provide flight guidance to prevent
airspeed decay below safe operating values during take-off and
go-around maneuvers when a single engine failure occurs while in
ALT CAP vertical guidance mode.
SUMMARY OF THE INVENTION
[0006] The present disclosure provides methods and systems for
providing vertical flight guidance for an aircraft. The methods and
systems described herein provide airspeed protection during
take-off and/or go-around maneuvers following an engine failure
while an altitude capture (ALT CAP) vertical guidance mode is
active. The methods and systems described herein provide flight
guidance capable to automatically pitch down the aircraft in order
to prevent airspeed decay below safe operating values during
take-off (e.g., takeoff safety speed) and/or go-around maneuvers
(e.g., missed approach climb speed) when a single engine failure
occurs while in the ALT CAP vertical guidance mode.
[0007] In accordance with a broad aspect, there is provided a
computer-implemented method for providing vertical flight guidance
for an aircraft. The method comprises providing, by a computer,
vertical flight guidance for the aircraft in an altitude capture
mode for commanding the aircraft to capture a target altitude. The
method comprises detecting, by the computer, at least one engine
inoperative condition while in the altitude capture mode. The
method comprises, in response to detecting the at least one engine
inoperative condition, the computer transitioning the vertical
flight guidance for the aircraft from the altitude capture mode to
a flight level change mode and providing vertical flight guidance
in the flight level change mode for commanding the aircraft to
capture the target altitude while maintaining airspeed of the
aircraft substantially at a target airspeed.
[0008] In some embodiments, detecting the at least one engine
inoperative condition comprises detecting the at least one engine
inoperative condition at takeoff.
[0009] In some embodiments, the target airspeed is a takeoff safety
speed of the aircraft.
[0010] In some embodiments, the target airspeed is a takeoff safety
speed of the aircraft plus a predetermined value.
[0011] In some embodiments, detecting the at least one engine
inoperative condition comprises detecting the at least one engine
inoperative condition at a time of a go-around maneuver.
[0012] In some embodiments, providing vertical flight guidance in
the flight level change mode comprises maintaining airspeed of the
aircraft substantially at a go-around speed of the aircraft with
one engine inoperative.
[0013] In some embodiments, detecting the at least one engine
inoperative condition comprises detecting the at least one engine
inoperative condition when airspeed of the aircraft is below an
airspeed threshold.
[0014] In some embodiments, the flight level change mode is a
second flight level change mode having a higher vertical
acceleration limit than a vertical acceleration limit of a first
flight level change mode and a lower minimum vertical speed level
than a minimum vertical speed level of the first flight level
change mode; and wherein the method further comprises
transitioning, by the computer, the second flight level change mode
to the first flight level change mode when airspeed is above the
airspeed threshold.
[0015] In some embodiments, the airspeed threshold is a takeoff
safety speed of the aircraft.
[0016] In some embodiments, the airspeed threshold is a missed
approach climb speed of the aircraft with one engine
inoperative.
[0017] In some embodiments, detecting the at least one engine
inoperative condition comprises detecting the at least one engine
inoperative condition when complemented deceleration of the
aircraft drops below a deceleration threshold.
[0018] In some embodiments, the flight level change mode is a
second flight level change mode having a higher vertical
acceleration limit than a vertical acceleration limit of a first
flight level change mode and a lower minimum vertical speed level
than a minimum vertical speed level of the first flight level
change mode; and wherein the method further comprises
transitioning, by the computer, the second flight level change mode
to the first flight level change mode when complemented
deceleration is above the deceleration threshold.
[0019] In some embodiments, the deceleration threshold is 1.18
kts/s.
[0020] In some embodiments, the method further comprises
transitioning, by the computer, the first flight level change mode
to the second flight level change mode when complementary filtered
airspeed of the aircraft is below a takeoff safety speed minus 3
knots, aircraft altitude is below a reference altitude by a set
altitude amount, and aircraft altitude is below the target
altitude.
[0021] In some embodiments, the method further comprises
transitioning, by the computer, the first flight level change mode
to the second flight level change mode when complementary filtered
airspeed of the aircraft is below a missed approach climb speed
minus 3 knots, aircraft altitude is below a reference altitude by a
set altitude amount, and aircraft altitude is below the target
altitude.
[0022] In some embodiments, wherein providing vertical flight
guidance in the second flight level change mode comprises:
providing vertical flight guidance for commanding the aircraft to
maintain a vertical speed of the aircraft above 100 ft/min; and
providing vertical flight guidance for commanding the aircraft to
limit a vertical acceleration of the aircraft below 0.4 G.
[0023] In some embodiments, providing vertical flight guidance
comprises providing visual cues on a display device for a pilot to
control the aircraft.
[0024] In some embodiments, providing vertical flight guidance
comprises providing commands to an autopilot computer for
controlling the aircraft.
[0025] In accordance with another broad aspect, there is provided
system for providing vertical flight guidance for an aircraft. The
system comprises a processing unit and a non-transitory
computer-readable memory having stored thereon program instructions
executable by the processing unit. The program instructions are
executable by the processing unit for: providing vertical flight
guidance for the aircraft in an altitude capture mode for
commanding the aircraft to capture a target altitude; detecting at
least one engine inoperative condition while in the altitude
capture mode; and in response to detecting the at least one engine
inoperative condition, transitioning the vertical flight guidance
for the aircraft from the altitude capture mode to a flight level
change mode and providing vertical flight guidance in the flight
level change mode for commanding the aircraft to capture the target
altitude while maintaining airspeed of the aircraft substantially
at a target airspeed.
[0026] In some embodiments, detecting the at least one engine
inoperative condition comprises detecting the at least one engine
inoperative condition at takeoff.
[0027] In some embodiments, the target airspeed is a takeoff safety
speed of the aircraft.
[0028] In some embodiments, the target airspeed is a takeoff safety
speed of the aircraft plus a predetermined value.
[0029] In some embodiments, detecting the at least one engine
inoperative condition comprises detecting the at least one engine
inoperative condition at a time of a go-around maneuver.
[0030] In some embodiments, providing vertical flight guidance in
the flight level change mode comprises maintaining airspeed of the
aircraft substantially at a go-around speed of the aircraft with
one engine inoperative.
[0031] In some embodiments, detecting the at least one engine
inoperative condition comprises detecting the at least one engine
inoperative condition when airspeed of the aircraft is below an
airspeed threshold.
[0032] In some embodiments, the flight level change mode is a
second flight level change mode having a higher vertical
acceleration limit than a vertical acceleration limit of a first
flight level change mode and a lower minimum vertical speed level
than a minimum vertical speed level of the first flight level
change mode; and wherein the program instructions are further
executable by the processing unit for transitioning the second
flight level change mode to the first flight level change mode when
airspeed is above the airspeed threshold.
[0033] In some embodiments, the airspeed threshold is a takeoff
safety speed of the aircraft.
[0034] In some embodiments, the airspeed threshold is a missed
approach climb speed of the aircraft with one engine
inoperative.
[0035] In some embodiments, detecting the at least one engine
inoperative condition comprises detecting the at least one engine
inoperative condition when complemented deceleration of the
aircraft drops below a deceleration threshold.
[0036] In some embodiments, the flight level change mode is a
second flight level change mode having a higher vertical
acceleration limit than a vertical acceleration limit of a first
flight level change mode and a lower minimum vertical speed level
than a minimum vertical speed level of the first flight level
change mode; and wherein the program instructions are further
executable by the processing unit for transitioning the second
flight level change mode to the first flight level change mode when
complemented deceleration is above the deceleration threshold.
[0037] In some embodiments, the deceleration threshold is 1.18
kts/s.
[0038] In some embodiments, the program instructions are further
executable by the processing unit for transitioning the first
flight level change mode to the second flight level change mode
when complementary filtered airspeed of the aircraft is below a
takeoff safety speed minus 3 knots, aircraft altitude is below a
reference altitude by a set altitude amount, and aircraft altitude
is below the target altitude.
[0039] In some embodiments, the program instructions are further
executable by the processing unit for transitioning the first
flight level change mode to the second flight level change mode
when complementary filtered airspeed of the aircraft is below a
missed approach climb speed minus 3 knots, aircraft altitude is
below a reference altitude by a set altitude amount, and aircraft
altitude is below the target altitude.
[0040] In some embodiments, providing vertical flight guidance in
the second flight level change mode comprises: providing vertical
flight guidance for commanding the aircraft to maintain a vertical
speed of the aircraft above 100 ft/min; and providing vertical
flight guidance for commanding the aircraft to limit a vertical
acceleration of the aircraft below 0.4 G.
[0041] In some embodiments, providing vertical flight guidance
comprises providing visual cues on a display device for a pilot to
control the aircraft.
[0042] In some embodiments, providing vertical flight guidance
comprises providing commands to an autopilot computer for
controlling the aircraft.
[0043] Features of the systems, devices, and methods described
herein may be used in various combinations, and may also be used
for the system and computer-readable storage medium in various
combinations.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] Further features and advantages of embodiments described
herein may become apparent from the following detailed description,
taken in combination with the appended drawings, in which:
[0045] FIG. 1 is a diagram of an example aircraft;
[0046] FIG. 2 is a flowchart of a method for providing vertical
flight guidance for an aircraft in accordance with an
embodiment;
[0047] FIG. 3 is a block diagram of an example computing device;
and
[0048] FIG. 4 is a block diagram of an example flight guidance
system comprising the computing device of FIG. 3.
[0049] It will be noted that throughout the appended drawings, like
features are identified by like reference numerals.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0050] Methods and systems for providing vertical flight guidance
for an aircraft are described herein. The methods and systems
described herein provide airspeed protection during take-off and/or
go-around maneuvers following an engine failure while an altitude
capture (ALT CAP) vertical guidance mode is active. The methods and
systems described herein provide flight guidance capable to
automatically pitch down the aircraft in order to prevent airspeed
decay below safe operating values during take-off (e.g., takeoff
safety speed) and/or go-around maneuvers (e.g., missed approach
climb speed) when a single engine failure occurs while in the ALT
CAP vertical guidance mode.
[0051] With reference to FIG. 1, an exemplary aircraft 10 is shown.
The aircraft 10 may be any type of aircraft such as a propeller
plane, jet plane, turbojet plane, turbo-propeller plane, and the
like. For example, the aircraft 10 may be a narrow-body,
twin-engine jet airliner. The aircraft 10 may be a fixed-wing
aircraft. The aircraft 10 may comprise flight control components
16, wings 31, 32, fuselage 18, engines 20 and empennage 22 of known
or other type. The flight control components 16 may comprise
ailerons, elevators, and a rudder. In the embodiment illustrated, a
single engine 20 is mounted under each of the wings 31, 32.
However, two or more engines 20 may be mounted to one or more of
wings 31, 32. Alternatively, or in addition, one or more engines 20
may be mounted to fuselage 18 or be installed on the aircraft 10 in
any suitable manner A cockpit 12 may be positioned at any suitable
location on the aircraft 10, for example at a front portion of the
fuselage 18. The cockpit 12 is configured for accommodating one or
more pilots who control the operation of the aircraft 10 by way of
one or more operator controls.
[0052] With reference to FIG. 2, there is illustrated a flowchart
of an example method 200 for providing vertical flight guidance for
an aircraft, such as the aircraft 10 of FIG. 1. While the method
200 is described herein with reference to the aircraft 10, the
method 200 may be applied to other types of aircraft. In accordance
with an embodiment, the vertical flight guidance is provided by a
flight guidance system, which may be any suitable aircraft
computer, device and/or system. For example, the flight guidance
system may comprise an Automatic Flight Control System (AFCS). The
flight guidance system is described in further detail elsewhere in
this document. The vertical flight guidance provided by method 200
may comprise providing commands to an autopilot computer for
controlling the aircraft 10 and/or providing visual cues on a
display device for the pilot to control the aircraft 10.
[0053] At step 202, vertical flight guidance for the aircraft 10 is
provided in the ALT CAP mode for commanding the aircraft 10 to
capture a target altitude. Capturing the target altitude refers to
climbing/ascending the aircraft 10 to the target altitude. The
target altitude may be determined by an aircraft computer or
selected by the pilot. For example, after liftoff of the aircraft
10, the flight guidance system switches from a take-off mode to the
altitude capture mode to ascend to the target altitude. In the
altitude capture mode, airspeed of the aircraft is controlled by
engine thrust control. The engine thrust control may be an
automatic throttle controlled by an aircraft computer (e.g., the
autothrottle computer) or a manual throttle (e.g., a throttle lever
angle (TLA)) controlled by the pilot. Similarly, for example, the
flight guidance may be provided in altitude capture mode to ascend
the aircraft 10 to the target altitude during a go-around maneuver.
In accordance with an embodiment, the altitude capture mode
provides vertical flight guidance commands to the autopilot
computer for automatically commanding the aircraft 10 to capture
the target altitude.
[0054] At step 204, while in the altitude capture mode, at least
one engine inoperative condition is detected. In accordance with an
embodiment, engine operability of the aircraft 10 is monitored to
detect the one engine inoperative condition. Engine operability
refers to the operative or inoperative status of the engines 20 of
the aircraft 10. For example, the condition when all of the engines
20 are operative may be referred to as all engines operative (AEO)
and the condition when one of the engines 20 is inoperative may be
referred to as one engine inoperative (OEI). The engine operability
may be monitored either dynamically in real time when needed,
regularly in accordance with any predetermined time interval, or
irregularly. The engine operability may be actively retrieved, or
may be passively received. For example, the engine operability may
be retrieved and/or received from one or more measuring devices
comprising one or more sensors for measuring engine operability. By
way of another example, the engine operability may be retrieved
and/or received from a control system or aircraft/engine computer.
In some embodiments, the engine operability is obtained via
existing components of the engines 20. In some embodiments, step
204 comprises triggering measurement of the engine operability
whenever method 200 is initiated.
[0055] At step 206, in response to detecting the at least one OEI
condition, the vertical flight guidance for the aircraft is
transitioned from the altitude capture mode to a flight level
change (FLC) mode. The transitions from the altitude capture mode
to the FLC mode is done automatically by the flight guidance system
and/or any other suitable aircraft computer without pilot
intervention. By automatically transitioning from the altitude
capture mode to the FLC mode and then providing flight guidance in
the FLC mode, airspeed is prevented from decaying below safe
operating values during take-off and/or go-around maneuvers.
[0056] At step 208, vertical flight guidance is provided in the FLC
mode for commanding the aircraft 10 to capture the target altitude
while maintaining airspeed of the aircraft 10 substantially at a
target airspeed. In the FLC mode, airspeed of the aircraft 10 is
controlled by the elevators of the aircraft 10. In particular, in
the FLC mode, a pitch down command or a pitch up command may be
generated to cause the elevators to change a pitch of the aircraft
10 to control airspeed of the aircraft 10. The pitch down command
or the pitch up command may be generated depending on the target
airspeed relative to a current airspeed of the aircraft 10. The
airspeed control of the aircraft 10 in the FLC mode may be referred
to as speed-on-elevator control. Speed-on-elevator control is
designed to track an airspeed reference (i.e., the target
airspeed). The target airspeed may be a calibrated airspeed (CAS),
an indicated airspeed (IAS), a Mach number or the like.
Accordingly, in the FLC mode, flight guidance commands are
generated to substantially maintain the target airspeed based on
controlling the elevators of the aircraft 10. Substantially
maintaining the airspeed of the aircraft 10 at the target airspeed
refers to controlling the airspeed of the aircraft 10 at the target
airspeed within an acceptable range of deviation. For example, an
acceptable range of deviation may be .+-.1%, .+-.2%, .+-.3% or any
other suitable value. By way of another example, an acceptable
range of deviation may be .+-.2 kts, .+-.3 kts, .+-.4 kts, .+-.5
kts or any other suitable value.
[0057] The target airspeed may be set as a function of operating
conditions of the aircraft 10. The target airspeed may be set
through an on-board Flight Management System (FMS) or manually by
the crew using a Flight Control Panel (FCP). In some embodiments,
the target airspeed is set depending on whether the OEI condition
is detected at takeoff or at a time of a go-around maneuver. For
example, if the OEI condition is detected at takeoff, the target
airspeed may be set at a takeoff safety speed (V2) for the aircraft
10. V2 refers to the target climb speed to be attained at or before
a height of 35 feet above the runway during a continued take-off,
following an engine failure Similarly, if the OEI condition is
detected at takeoff, the target airspeed may be set at the takeoff
safety speed for the aircraft 10 plus a predetermined value. The
predetermined value may be 10 or 20 kts or any other suitable
value. The predetermined value may be selected to prevent speed
decay below the takeoff safety speed. In some embodiments, if there
is no engine failure (AEO) at take-off, the aircraft 10 would
accelerate to a minimum of V2+10 kts; then, if OEI occurs, the
target airspeed may be set at V2+10 kts. By way of another example,
if the OEI condition is detected at a time of a go-around maneuver,
the target airspeed may be set at a go-around speed (VGA) of the
aircraft 10. Setting the target airspeed to the VGA may prevent
speed decay below a missed approach climb speed (VAC). Other values
for setting the target airspeed are contemplated.
[0058] In accordance with an embodiment, the transition from the
altitude capture mode to the FLC mode is a transition into a second
FLC mode different from a transition into a first FLC mode. For
ease of readability, the first FLC mode is referred to herein as a
normal flight level change (NFLC) mode and the second FLC mode is
referred to herein as a forced flight level change (FFLC) mode. The
FFLC mode is a vertical flight guidance mode with control
parameters different from the NFLC mode. The NFLC mode corresponds
to a conventional FLC mode.
[0059] In some embodiments, in the FLC mode, a vertical speed of
the aircraft 10 is maintained above a minimum vertical speed level.
Accordingly, providing vertical flight guidance may comprise
commanding the aircraft 10 to maintain a vertical speed of the
aircraft above a minimum vertical speed level. For example, in the
context of the FFLC mode, the minimum vertical airspeed may be set
at 100 feet/min. The minimum vertical speed may be set depending on
operating conditions of the aircraft 10.
[0060] In some embodiments, in the FLC mode, a vertical
acceleration of the aircraft 10 is maintained below a vertical
acceleration limit Accordingly, providing vertical flight guidance
may comprise commanding the aircraft 10 to limit the vertical
acceleration of the aircraft below the vertical acceleration limit
In accordance with an embodiment, in the context of the FFLC mode,
the vertical acceleration limit is set at 0.4 G. The vertical
acceleration limit may be set at other values (e.g., 0.3 G, 0.18 G,
or any other suitable value), which may depend on dynamics of the
aircraft 10. The 0.4 G vertical acceleration limit has been found
to typically not induce passenger discomfort and provides a more
aggressive pitch down to rectify the speed decay situation relative
to NFLC mode which typically has a vertical acceleration limit of
0.1 G. The vertical acceleration limit may be set depending on
operating conditions of the aircraft 10. Accordingly, in some
embodiments, the FLC mode has a set of control parameters that may
be adjusted and/or set depending on operating conditions. The
control parameters may comprise the target airspeed, the minimum
vertical speed level, the vertical acceleration limit and/or any
other suitable control parameters used in the operation of the FLC
mode.
[0061] The NFLC mode has a first set of control parameters and the
FFLC mode has a second set of control parameters. In accordance
with a specific and non-limiting example of implementation, the
first set of control parameters for the NFLC mode comprises the
minimum vertical speed level set at 250 feet/min below 20,000 feet
pressure altitude and the vertical acceleration limit set at 0.1 G.
In accordance with another specific and non-limiting example of
implementation, the second set of control parameters for the FFLC
mode comprises the minimum vertical speed level set at 100 feet/min
and the vertical acceleration limit set at 0.4 G. In the above
example, the FFLC mode has a higher vertical acceleration limit
than the vertical acceleration limit of the NFLC mode and a lower
minimum vertical speed level than the minimum vertical speed level
of the NFLC mode. It should be appreciated that, in the above
example, a more aggressive pitch down command is thus provided by
the FFLC mode compared to the NFLC mode for the purpose of
protecting the speed reference. For example, by setting the minimum
vertical speed level set at 100 feet/min in the FFLC mode, the
minimum vertical speed level may be set low enough to support
aggressive speed control but high enough to avoid negative vertical
acceleration. By way of another example, by setting the vertical
acceleration limit at 0.4 G, the vertical commands are generated to
aggressively nose over the aircraft to neutralize speed decay. The
control parameters of the NFLC and FFLC mode may vary depending on
practical implementation.
[0062] It should be appreciated that conventionally when an OEI
occurs in ALT CAP mode, pilot intervention is typically required to
push the nose of the aircraft down to rectify the speed decay
situation. However, for example, when AFCS pilot intervention is
not possible (e.g., for the reasons provided in the Background
section of this document), it is desirable for the AFCS to ensure
automatic airspeed protection through pitch command. While a crew
member could in theory manually actuate a FLC mode pushbutton on a
Flight Control Panel (FCP) to activate the NFLC mode, this has
drawbacks. For example, when a low altitude capture occurs it is
due of high rate of climb (i.e., light weight combined with
power-full thrust). Right after an ALT CAP OEI event occurs, the
rate of climb does not necessarily decrease immediately and it
takes a while (e.g., 10 to 20 seconds) for the rate of climb to
decrease depending of the current conditions of the aircraft. If
the crew transitions to NFLC mode through pressing FLC mode button
on the FCP, the flight guidance switches for an iteration to NFLC
mode but then switches immediately back to ALT CAP due to the rate
of climb which is still high. The crew would then have to wait an
undetermined period of time until the rate of climb decreases due
to the engine failure and only then press FLC button in order to
have the flight guidance stay in NFLC mode and recalculate the ALT
CAP point for a new (diminished) rate of climb. As such, it would
be unacceptable for a pilot to manually push the FLC mode button to
activate the NFLC mode. Accordingly, it is desirable for the flight
guidance system to make use of the already existing FLC flight
guidance vertical mode with modified control parameters designed
for timely and effective airspeed protection, thus automatically
transitioning the vertical guidance for the aircraft from the ALT
CAP mode to the FFLC mode. Thus, the flight guidance system and/or
any other suitable aircraft computer may automatically, without
pilot intervention (e.g., no pilot action on the FLC pushbutton on
the FCP), transition the vertical flight guidance for the aircraft
from the ALT CAP mode to an already existing FLC mode with the
control parameters modified.
[0063] In accordance with an embodiment, the vertical flight
guidance for the aircraft 10 is transitioned from the altitude
capture mode to the FFLC mode at step 206 in response to detecting
the at least one engine inoperative condition when airspeed of the
aircraft 10 is below an airspeed threshold. The airspeed may be the
CAS, IAS, Mach number or the like. The airspeed threshold may be
V2, VAC or any other suitable value. In some embodiments, while the
airspeed of the aircraft 10 is below the airspeed threshold, the
FFLC mode is used to provide flight guidance and then when the
airspeed is above the airspeed threshold, the FFLC mode is
transitioned from the FFLC mode to the NFLC mode. The airspeed
threshold may be set depending on operating conditions. In some
embodiments, the airspeed threshold is set at the target airspeed.
The airspeed threshold may vary depending on practical
implementations.
[0064] In some embodiments, the vertical flight guidance for the
aircraft is transitioned from the altitude capture mode to the FFLC
mode at step 206 in response to detecting the at least one engine
inoperative condition when complemented deceleration of the
aircraft drops below a deceleration threshold. Complemented
acceleration/deceleration refers to a longitudinal
acceleration/deceleration of the aircraft 10 complemented by a
filtered IAS of the aircraft 10 (e.g., from an air data system
probe). In some embodiments, while the complemented deceleration is
below the deceleration threshold, the FFLC mode is used and then
when the complemented deceleration is above the deceleration
threshold, the FFLC mode is transitioned from the FFLC mode to the
NFLC mode. The deceleration threshold may be set at 1.18 kts/s or
any other suitable value. In accordance with an embodiment,
computer simulation was used to determine that a deceleration
threshold of 1.18 kts/s is high enough to avoid nuisance activation
due to turbulence and low enough to detect a true deceleration as a
result of the OEI condition. Accordingly, the complemented
deceleration may be used to avoid an inadvertent transition to the
FFLC mode due to noisy inertial deceleration below the deceleration
threshold. The deceleration threshold may vary depending on
practical implementations.
[0065] In some embodiments, when the airspeed of the aircraft 10 is
below the airspeed threshold or when complemented deceleration of
the aircraft is below the deceleration threshold, the FFLC mode is
used to provide flight guidance. In some embodiments, when the
airspeed is above the airspeed threshold and when complemented
deceleration of the aircraft is above the deceleration threshold,
the FFLC mode is transitioned from the FFLC mode to the NFLC
mode.
[0066] In some embodiments, the vertical flight guidance for the
aircraft is transitioned from the NFLC mode to the FFLC mode when
complementary filtered airspeed of the aircraft is below a V2-3
(i.e., V2 minus 3 knots) or Vac-3 (i.e., VAC minus 3 knots) speed,
aircraft altitude is below a reference altitude by a set altitude
amount, and aircraft altitude is below the target altitude.
Complementary filtered airspeed refers to the airspeed of the
aircraft as outputted by an airspeed complementary filter. The
airspeed complementary filter uses IAS of the aircraft 10 and the
longitudinal acceleration of the aircraft 10 as inputs. The purpose
of the airspeed complementary filter is to filter out gust
components and restore high frequency components due to aircraft
maneuvering. The re-activation of FFLC mode may prevent unnecessary
transition to the NFLC mode when takeoff mode or go-around mode has
already commenced satisfactory speed tracking of the target
airspeed at V2 or VAC.
[0067] In some embodiments, when altitude of the aircraft 10 is
above a capture point of the target altitude, airspeed is above the
airspeed threshold, and complemented deceleration is above the
deceleration threshold, the FFLC mode is deactivated. In some
embodiments, when altitude of the aircraft 10 is above the target
altitude minus a predetermined amount (e.g., 100 feet), the FFLC
mode is deactivated. This may prevent altitude overshoot due to
unnecessary FFLC mode activation, or prevent toggling between FFLC
mode and ALT CAP mode. Unnecessary FFLC activation may in turn be
avoided and selection of other vertical modes allowed, thereby
preventing latent activation after takeoff or go-around phase is
complete.
[0068] With reference to FIGS. 3, the method 200 may be implemented
by a computing device 310. The computing device 310 comprises a
processing unit 312 and a memory 314 which has stored therein
computer-executable instructions 316. The processing unit 312 may
comprise any suitable devices configured to implement the method
200 such that instructions 316, when executed by the computing
device 310 or other programmable apparatus, may cause the
functions/acts/steps performed as part of the method 200 as
described herein to be executed. The processing unit 312 may
comprise, for example, any type of general-purpose microprocessor
or microcontroller, a digital signal processing (DSP) processor, a
central processing unit (CPU), an integrated circuit, a field
programmable gate array (FPGA), a reconfigurable processor, other
suitably programmed or programmable logic circuits, or any
combination thereof
[0069] The memory 314 may comprise any suitable known or other
machine-readable storage medium. The memory 314 may comprise
non-transitory computer readable storage medium, for example, but
not limited to, an electronic, magnetic, optical, electromagnetic,
infrared, or semiconductor system, apparatus, or device, or any
suitable combination of the foregoing. The memory 314 may include a
suitable combination of any type of computer memory that is located
either internally or externally to device, for example
random-access memory (RAM), read-only memory (ROM), compact disc
read-only memory (CDROM), electro-optical memory, magneto-optical
memory, erasable programmable read-only memory (EPROM), and
electrically-erasable programmable read-only memory (EEPROM),
Ferroelectric RAM (FRAM) or the like. Memory 314 may comprise any
storage means (e.g., devices) suitable for retrievably storing
machine-readable instructions 316 executable by processing unit
312.
[0070] The methods and systems for providing flight guidance
described herein may be implemented in a high level procedural or
object oriented programming or scripting language, or a combination
thereof, to communicate with or assist in the operation of a
computer system, for example the computing device 310.
Alternatively, the methods and systems for providing flight
guidance may be implemented in assembly or machine language. The
language may be a compiled or interpreted language. Program code
for implementing the methods and systems for providing flight
guidance may be stored on a storage media or a device, for example
a ROM, a magnetic disk, an optical disc, a flash drive, or any
other suitable storage media or device. The program code may be
readable by a general or special-purpose programmable computer for
configuring and operating the computer when the storage media or
device is read by the computer to perform the procedures described
herein. Embodiments of the methods and systems for providing flight
guidance may also be considered to be implemented by way of a
non-transitory computer-readable storage medium having a computer
program stored thereon. The computer program may comprise
computer-readable instructions which cause a computer, or more
specifically the processing unit 312 of the computing device 310,
to operate in a specific and predefined manner to perform the
functions described herein, for example those described in the
method 200. Computer-executable instructions may be in many forms,
including program modules, executed by one or more computers or
other devices. Generally, program modules include routines,
programs, objects, components, data structures, etc., that perform
particular tasks or implement particular abstract data types.
Typically the functionality of the program modules may be combined
or distributed as desired in various embodiments.
[0071] With reference to FIG. 4, the method 200 may be implemented
by a flight guidance system 400 comprising the computing device
310. In some embodiments, the system 400 is connected (e.g., over
one or more buses) to and/or comprises one or more sensors 402, an
aircraft display 404, an air data computer 406, and/or an autopilot
computer 408. In accordance with an embodiment, the computing
device 310 processes inputs from the one or more sensors 402 and/or
the air data computer 406 to determine flight guidance commands.
The computing device 310 then provides the flight guidance commands
to the aircraft display 404 and/or the autopilot computer 408. In
some embodiments, the computing device 310 implements the autopilot
functionality of the autopilot computer 408. Accordingly, the
flight guidance system 400 may be referred to as an automatic
flight control system (AFCS), a flight guidance control system
(FGCS), and/or by any other suitable nomenclature.
[0072] The aircraft display 404 may comprise any kind of display
such as an LCD (liquid crystal display), an LED (light emitting
diode) display, a CRT (cathode ray tube) display, a HUD (Heads-up
Display), a PFD (primary flight display), and/or any other suitable
display device. A HUD is any transparent display that presents data
in the pilot or co-pilot's field of vision without obstructing the
view. A PFD is an aircraft instrument dedicated to flight
information. The aircraft display 404 may display the vertical
flight guidance for the aircraft as calculated by the computing
device 310. Accordingly, the computing device 310 may cause a
graphical user interface (GUI) to display the vertical flight
guidance commands for the aircraft 10 on the aircraft display 400.
In some embodiments, the aircraft display 404 is separate from the
system 400 and/or may be an existing part of the aircraft 10. The
aircraft display 404 may be operably coupled to the computing
device 310 by one or more data buses such that the computing device
310 may provide the vertical flight guidance and/or other suitable
parameters to the aircraft display 400.
[0073] In some embodiments, the flight guidance system 400 sets an
ALT CAP signal to TRUE when the altitude capture mode is activated
(e.g., step 202 of FIG. 2) and to FALSE when the altitude capture
mode is deactivated (e.g., step 206 of FIG. 2). In some
embodiments, the flight guidance system 400 receives and/or
generates an OEI signal indicative of the OEI condition when one
engine is inoperative (e.g., step 204 of FIG. 2). For example, the
OEI signal may be set to TRUE when one engine is inoperative and to
FALSE when all engines are operative. In some embodiments, the
flight guidance system 400 detects when both the OEI signal is TRUE
and the ALT CAP signal is TRUE (e.g., step 206 of FIG. 2), and then
sets an FLC signal to TRUE. In some embodiments, when the FLC
signal is set to TRUE, the flight guidance system 400 provides
flight guidance according to the FLC mode (e.g., step 208 of FIG.
2). In some embodiments, the flight guidance system 400 determines
that the conditions for activating the FFLC mode are present (e.g.,
when airspeed of the aircraft 10 is below the airspeed threshold or
when complemented deceleration of the aircraft is below the
deceleration threshold), and then sets FFLC signal to TRUE.
Otherwise, if it is determined that the conditions for activating
the FFLC mode are not present, the FFLC signal is set to FALSE. In
some embodiments, when the FFLC signal is TRUE, the FLC mode
operates according to the control parameters for FFLC; otherwise,
when the FFLC signal is FALSE and the FLC signal is TRUE, the FLC
mode operates according to the control parameters for NFLC. In some
embodiments, the flight guidance system 400 determines that the
conditions for deactivating the FFLC mode are present (e.g., when
airspeed of the aircraft 10 is above the airspeed threshold and/or
when complemented deceleration of the aircraft is above the
deceleration threshold), and then sets the FFLC signal to FALSE.
Accordingly, the FFLC mode is activated when FFLC signal is TRUE
and deactivated when the FFLC signal is FALSE.
[0074] In some embodiments, the FFLC mode has a state. The state
may be active, reset, re-activation, or disabled. For example, when
the FFLC mode is activated, the FFLC state may be set to active.
When the FFLC mode transitions to the NFLC mode, the FFLC state may
be set to reset. When the NFLC mode transitions back to the FFLC
mode, the FFLC state may be set to re-activation. When operating in
the altitude capture mode, the FFLC state may be set to
disabled.
[0075] The operating conditions of the aircraft 10 used for
setting, updating, and adjusting the various parameters described
herein may comprise one or more of a state of the aircraft 10
(e.g., takeoff, go-around maneuver, landing and the like), airspeed
(e.g., CAS, IAS, Mach and the like), altitude, engine operability
(e.g., AEO, OEI and the like), vertical speed, vertical
acceleration rate and/or any other suitable operating
conditions.
[0076] In some embodiments, both the FFLC mode and the NFLC mode
are displayed as FLC on a flight mode annunciation (FMA) vertical
mode field of the flight guidance system.
[0077] In some embodiments, when the FFLC mode is active, all other
vertical modes are disabled except for underspeed protection (USPD)
mode and windshear (WSHR) mode. The USPD mode may be on Flight
Guidance (FG) or on Autothrottle (A/T). In this example, reference
is made to the FG USPD mode, when speed decreases below a limit
called Vmintrim, the FG USPD mode activates to pitch the aircraft
10 down. With FFLC protecting against V2 in takeoff which is
typically higher than Vmintrim; however, in the unlikely case that
FFLC is unable to protect the airspeed decay and the airspeed of
the aircraft 10 reaches the Vmintrim threshold, in this example,
the USPD mode is activated to take priority over FFLC.
[0078] Computer simulation, modeling, engineering simulators and/or
processing may be used to determine the various parameters
described herein. For example, computer simulation, modeling,
engineering simulators and/or processing may be used to determine
the predetermined value, the control parameters, the target
airspeed, the minimum vertical speed level, the vertical
acceleration limit, etc. In some embodiments, computer simulations,
modeling, engineering simulators and/or processing are performed to
determine the control parameters for the FFLC mode and/or the NFLC
mode. For example, the control parameters for the FFLC mode may be
determined from computer simulations, modeling, engineering
simulators and/or processing such that the control parameters
prevent negative vertical rates and/or to manage altitude overshoot
(e.g., by +150 feet).
[0079] The above description is meant to be exemplary only, and one
skilled in the art will recognize that changes may be made to the
embodiments described without departing from the scope of the
invention disclosed. Still other modifications which fall within
the scope of the present invention will be apparent to those
skilled in the art, in light of a review of this disclosure.
[0080] Various aspects of the methods and systems for providing
flight guidance for an aircraft may be used alone, in combination,
or in a variety of arrangements not specifically discussed in the
embodiments described in the foregoing and is therefore not limited
in its application to the details and arrangement of components set
forth in the foregoing description or illustrated in the drawings.
For example, aspects described in one embodiment may be combined in
any manner with aspects described in other embodiments. Although
particular embodiments have been shown and described, it will be
obvious to those skilled in the art that changes and modifications
may be made without departing from this invention in its broader
aspects. The scope of the following claims should not be limited by
the embodiments set forth in the examples, but should be given the
broadest reasonable interpretation consistent with the description
as a whole.
[0081] While at least one exemplary embodiment of the present
invention(s) is disclosed herein, it should be understood that
modifications, substitutions and alternatives may be apparent to
one of ordinary skill in the art and can be made without departing
from the scope of this disclosure. This disclosure is intended to
cover any adaptations or variations of the exemplary embodiment(s).
In addition, in this disclosure, the terms "comprise" or
"comprising" do not exclude other elements or steps, the terms "a"
or "one" do not exclude a plural number, and the term "or" means
either or both. Furthermore, characteristics or steps which have
been described may also be used in combination with other
characteristics or steps and in any order unless the disclosure or
context suggests otherwise. This disclosure hereby incorporates by
reference the complete disclosure of any patent or application from
which it claims benefit or priority.
* * * * *